This invention relates to locking handles for cocks and valves employed in air brake systems for railway trains and, particularly, to two-piece-type locking handles designed to discourage or protect against unintentional operation of the cocks.
Angle cocks are provided at the ends of railway car brake pipes, for example, to open the air connection between adjoining cars of the train and to close the air connection at the last car to thereby permit fluid pressure brake control at each car in the train by increasing and decreasing the brake pipe pressure from the locomotive at the head of the train.
In the event an angle cock intermediate the ends of the train is closed, the brake pipe pressure is cut off from the cars behind the closed angle cock, thereby rendering these cars absent of brake control. Also, closure of the angle cock at the head of the train will prevent the increase and decrease of brake pipe pressure from being reflected throughout the entire length of train, so that the train is without any brake control whatsoever.
Conventional, two-piece locking handles have been designed to lock the handle against accidental movement from either an open or closed position. These self-locking or gravity lock handles are pivotally connected for operation in a vertical plane in which the handle is free to be raised from a locking position to an unlocked position. Locking lugs on the handle are free to clear stops on the housing in the raised position of the handle to permit rotational movement of the handle horizontally, and thereby effect opening and closing of the valve. This design relies upon the weight of the handle to maintain the handle in its lower locked position by gravity. The gravity lock design has been proven adequate through years of in-service operation. However, many railroads are now specifying a spring-locking handle. To date, any spring-locking handle design utilizing the detail parts long standard with the gravity lock design have not been economical to manufacture.